In our last topic, we saw that we want to help our physical and spiritual children learn to explain that Abraham and Sarah were both rebuked for telling a lie. Abimelech chose to show kindness to them and let them know they were forgiven. This confession of sin led to the fulfillment of the promise of God to Abraham that the Lord would give a son to Sarah. Through that son would come One who would bring blessing to all nations.

God had promised Abraham and Sarah a son. Now, the time had come for that son to be conceived and be born. Genesis 21:1-4 says, “And the Lord visited Sarah as He had said, and the Lord did for Sarah as He had spoken. For Sarah conceived and bore Abraham a son in his old age, at the set time of which God had spoken to him. And Abraham called the name of his son who was born to him—whom Sarah bore to him—Isaac. Then Abraham circumcised his son Isaac when he was eight days old, as God had commanded him.” God had promised Abraham and Sarah in Genesis 12:1-4 that God would make a great nation from them. At that time, Abraham was seventy-five years old and Sarah was sixty-five years old. Now, after twenty-five years, they finally had the son who was going to make it possible for that great nation to come into existence.

We read that the Lord visited Sarah. The word translated “visited” is translated by several different words but the word means to exercise oversight over one who is a helper. Potiphar bought Joseph as a slave. Genesis 39:3-5 says, “And his master saw that the Lord was with him and that the Lord made all he did to prosper in his hand. So Joseph found favor in his sight, and served him. Then he made him overseer of his house, and all that he had he put under his authority. So it was, from the time that he had made him overseer of his house and all that he had, that the Lord blessed the Egyptian’s house for Joseph’s sake; and the blessing of the Lord was on all that he had in the house and in the field.” In these verses, the word is translated “overseer” twice because Joseph was placed in charge of the other servants. Here, in these verses, we see that God was exercising oversight over Sarah and fulfilling the promise He had made twenty-five years earlier that He would give Abraham and Sarah a son from which that nation would come.

The Lord had reminded Abraham of that promise more than a year earlier, when He said to Abraham in Genesis 18:10, “And He said, ‘I will certainly return to you according to the time of life, and behold, Sarah your wife shall have a son.’ (Sarah was listening in the tent door which was behind him.)” God now caused that promise to be fulfilled as Sarah conceived and bore Abraham a son. Abraham named that son Isaac. In chapter 17, God told Abraham to circumcise all of the male children born in his house. Genesis 17:12 says, “‘He who is eight days old among you shall be circumcised, every male child in your generations, he who is born in your house or bought with money from any foreigner who is not your descendant.’” Abraham was obedient to this command, so he circumcised Isaac when he was eight days old.

Genesis 21:5-7 says, “Now Abraham was one hundred years old when his son Isaac was born to him. And Sarah said, ‘God has made me laugh, and all who hear will laugh with me.’ She also said, ‘Who would have said to Abraham that Sarah would nurse children? For I have borne him a son in his old age.’” Here, we see that Abraham was one hundred years old, which meant that Sarah was ninety years old at the time Isaac was born. The name “Isaac” means he laughs. The reason why he was given that name is explained, in Genesis 18:11-12, where we read, “Now Abraham and Sarah were old, well advanced in age; and Sarah had passed the age of childbearing. Therefore Sarah laughed within herself, saying, ‘After I have grown old, shall I have pleasure, my lord being old also?’” Here, we see that Sarah laughed within herself. God had said at that time in Genesis 18:14, “Is anything too hard for the Lord? At the appointed time I will return to you, according to the time of life, and Sarah shall have a son.” Now, that son had arrived.

We see that Sarah conceived at the set time God had said the baby would be conceived. Sarah had laughed within herself when she heard she was going to give birth to a son even though it was past the time when she could conceive a child. Now, she said God was the One who had made her laugh. The word that is translated “laugh” can refer to a laugh of amazement and joy or a laugh of mocking. It is used to refer to the laughter of mocking, in Genesis 39:14, where the wife of Potiphar accused Joseph falsely to cover her own sin after she tried to seduce Joseph, “...she called to the men of her house and spoke to them, saying, ‘See, he has brought in to us a Hebrew to mock us. He came in to me to lie with me, and I cried out with a loud voice.’” We will also see the word used for mocking in the next verses when we read in Genesis 21:9, “And Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, scoffing.”

In contrast, in the verses in Genesis 17, Genesis 18, and this verse, the word is used to speak of the laughter of amazement and joy. Both Abraham and Sarah had been filled with amazement and joy when they first heard the promise that Isaac would be born at the set time. Now that the son had arrived, Sarah again had this laugh of amazement and joy as she thought about the way the Lord had worked in her life. She also said that others would join her and celebrate with the laughter of amazement and joy when they heard that Sarah had given birth to a son after all of these years she had been married to Abraham. This reminds us that this was a time of great celebration for Abraham and Sarah as they saw how the Lord had worked in their lives and given them this son.

As Sarah gave additional thought to what had happened to them, Sarah said, “Who would have said to Abraham that Sarah would nurse children? For I have borne him a son in his old age.” Sarah immediately thought of what individuals would say when they heard that she had given birth to a baby in her old age. Hebrews 11:11 explains why Sarah was able to have a son even in her old age. That verse says, “By faith Sarah herself also received strength to conceive seed, and she bore a child when she was past the age, because she judged Him faithful who had promised.” This verse teaches an important lesson about faith. Sarah recognized that God is faithful and will carry out every specific promise that He has given. Since God had promised her a son, she had faith that God would give her a son. Faith is the confident assurance that God will do exactly what He has promised.

Genesis 21:8-10 says, “So the child grew and was weaned. And Abraham made a great feast on the same day that Isaac was weaned. And Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, scoffing. Therefore she said to Abraham, ‘Cast out this bondwoman and her son; for the son of this bondwoman shall not be heir with my son, namely with Isaac.’” In that day, it was normal to wean a child when the child was about two years old. This was an event that had great importance in that time because it was a sign that the child had gone from infancy to childhood. Psalm 131:2 says, “Surely I have calmed and quieted my soul, like a weaned child with his mother; like a weaned child is my soul within me.” In this verse, we see that a child was old enough to understand and accept the fact that he or she was no longer an infant.

Abraham and Sarah celebrated the fact that Isaac had been weaned with a great feast on the day that he was weaned. This also meant that he had been instructed about the fact that he would now be treated as a child, instead of an infant. However, everything did not go as planned on this day and something happened that was going to cause conflict between Abraham, Sarah, and Hagar. Ishmael had been born fourteen years before Isaac. That meant that he was now about sixteen years old. Instead of showing the laughter of joy mentioned earlier, Sarah saw him showing the laughter of mocking or scoffing. We do not know exactly what he said or did. However, he may have been saying things like, “You are not a big boy” or “You are still a baby” in order to try and make Isaac cry. Perhaps he was doing things by his actions that mocked Isaac. Whatever he was saying or doing, Sarah saw his actions or heard his words and became very upset.

As a result, Sarah said, “Cast out this bondwoman and her son; for the son of this bondwoman shall not be heir with my son, namely with Isaac.” This statement by Sarah is used to give a very important illustration in the New Testament. Galatians 4:22-23 says, “For it is written that Abraham had two sons: the one by a bondwoman, the other by a freewoman. But he who was of the bondwoman was born according to the flesh, and he of the freewoman through promise.” Sarah had tried to get an heir for Abraham by suggesting sin. As a result, Ishmael was born as a result of worldly thinking. In contrast, God had promised Abraham and Sarah that they would have a son. This son was born after it was humanly impossible for Sarah to have a son. As a result, this was a promise to fulfill the will of God. This day, they were honoring that child and Ishmael was mocking.

As a result, Sarah did not even mention the mother or the name of Ishmael that day. Instead, she just said “Cast out the bondwoman and her son.” Israel was under the Old Covenant, which was the Law. Christ came to fulfill the Law and set us free from the Law. As a result, Galatians 4:30-31 says, “Nevertheless what does the Scripture say? ‘Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman.’ So then, brethren, we are not children of the bondwoman but of the free.” Then, 1 Corinthians 11:25 adds, “In the same manner He also took the cup after supper, saying, ‘This cup is the new covenant in My blood. This do, as often as you drink it, in remembrance of Me.’” The Old Covenant was the Law that shows that all mankind is guilty of sin. The New Covenant was made possible by the blood of Christ and sets us free from the Law. We want to help our physical and spiritual children learn to explain why this illustration is so important for every person to understand. This will help them to explain why faith in Christ sets us free from the Law. May the Lord richly bless you as you help your children learn to explain this illustration.